Catalytic Performance of Limonite Ores in the Decomposition of Model Compounds of Biomass-Derived Tar

Tsubouchi, Naoto; Mochizuki, Yuuki; Byambajav, Enkhsaruul; Takahashi, Satoko; Hanaoka, Yuu; Ohtsuka, Yasuo

Catalytic Performance of Limonite Ores in the Decomposition of Model Compounds of Biomass-Derived Tar

2017

Catalytic decomposition of toluene (C₆H₅CH₃) or benzene (C₆H₆) with inexpensive limonite ores, composed mainly of goethite (α-FeOOH), was examined using a vertical, cylindrical flow fixed-bed quartz reactor to develop a novel method of removing biomass-derived tar components. The unsupported limonite catalyst was active for the decomposition of 480 ppm of C₆H₅CH₃ and 1700 ppm of C₆H₆ in 15 vol % H₂O/45 vol % H₂/He, leading to C₆H₅CH₃ and C₆H₆ conversions at 500 °C of nearly 100 and 97%, respectively. When the C₆H₅CH₃ decomposition temperature was increased from 500 to 800 °C, the overall reaction path changed from demethylation to hydrocracking and then to steam reforming. A honeycomb-supported limonite catalyst also was effective and achieved nearly complete C₆H₅CH₃ conversion at 600 °C. In addition, the honeycomb-supported catalyst promoted C₆H₆ conversion of nearly 100% without carbon deposits at 700 °C in 15 vol % H₂O/20 vol % H₂/26 vol % CO/20 vol % CO₂/5 vol % CH₄ that was designed to simulate raw fuel gas derived from biomass gasification. Powder X-ray diffraction (XRD) measurements after reaction at 700–800 °C revealed the presence of finely dispersed metallic iron (α-Fe), which is likely responsible for the high catalytic performance.

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